L4 was promising but happened to not be suitable for implementing a general-purpose operating system on top of it. See port to l4 for the historical details.
Coyotos is abandoned upstream
Neal Walfield started working on a newly designed kernel called viengoos. Unfortunately, he currently lacks time and the projects it paused.
In the meanwhile, people are thus continuing with mach.
IRC, #hurd, 2011-01-12.
<Pete-J> Hello i am just curious of the development of Hurd - what's the
current mission on the microkernel i see projects like l4 and viengoos,
will one of these projects replace Mach? or will you stick with Mach
<Pete-J> as i understand is that Mach is a first generation microkernel
that's very old in design and causes alot of issues
<Pete-J> that's where l4 and viengoos comes in - they are trying to be the
next generation Mach - am i correct?
<neal> l4 is not a drop in replacement for Mach
<neal> it doesn't actually do much resource management
<neal> for instance, you still have to implement a memory manager
<neal> this is where several issues are with Mach
<neal> l4 doesn't address those issues; it punts to the operating system
<Pete-J> and what about viengoos?
<neal> it's unfinished
<neal> and it implemented some untested ideas
<neal> i.e., parts of viengoos were research
<neal> there has not been a sufficient evaluation of those ideas to
determine whether they are a good approach
<Pete-J> meaning that viengoos is a research kernel that could aid Mach?
<neal> I'm not sure I understand your question
<Pete-J> Well is viengoos trying to be a replacement for Mach, or will
viengoos be an experiment of new ideas that could be implemented in Mach?
<Pete-J> i am sorry for my limited english
<neal> viengoos was designed with a Hurd-like user-land in mind
<neal> in that sense it was a Mach replacement
<neal> (unlike L4)
<neal> viengoos consisted of a few experiments
<neal> one could implement them in mach
<neal> but it would require exposing new interfaces
<neal> in which case, I'm not sure you could call the result Mach
<Pete-J> Well as i understand you develop two microkernels side by side,
wouldnt it be more effective to investigate viengoos more and maybe move
the focus to viengoos?
<antrik> no
<antrik> having something working all the time is crucial
<antrik> it's very hard to motivate people to work on a project that might
be useful, in a couple of years, perhaps...
<Pete-J> Well Mach is meant to be replaced one day - i see no reason to
keep on developing it just because it works at this moment
<Pete-J> *if Mach is meant to be replaced
<antrik> it's not at all clear that it will be replaced by something
completely different. I for my part believe that modifying the existing
Mach is a more promising approach
<Pete-J> as i understand man power is something you need - and by spreading
out the developers just makes the progress more slow
<antrik> but even if it *were* to be replaced one day, it doesn't change
the fact that we need it *now*
<antrik> all software will be obsolete one day. doesn't mean it's not worth
working on
<antrik> the vast majority of work is not on the microkernel anyways, but
on the system running on top of it
<Pete-J> ahh i see
<antrik> manpower is not something that comes from nowhere. again, having
something working is crucial in a volunteer project like this
<antrik> there are no fixed plans